1. Field of the Invention
The present invention relates to a pattern writing apparatus and a pattern writing method for writing a pattern on a photosensitive material irradiated with a spatially modulated light.
2. Description of the Background Art
Conventionally known is a technique for writing a fine pattern on a photosensitive material by moving a spatially modulated light on the photosensitive material. A DMD (Digital Micromirror Device) with a micromirror group is proposed to be used as a spatial light modulator.
For example, Japanese Patent Application Laid-Open No. 2004-326076 (Document 1) discloses a technique where an array of an irradiation region group on a photosensitive material to which light from a micromirror group of a DMD is applied, is tilted relatively to a main scan direction and main scanning of the irradiation region group is performed to improve a resolution. In the apparatus of Document 1, the irradiation region group intermittently moves in the sub scan direction every time when main scanning of the irradiation region group is performed. In a case where the irradiation region group is tilted, the number of irradiation regions passing both sides (in the sub scan direction) of a strip region which is irradiated with light in one main scanning is smaller than that of the irradiation regions passing the central portion of the strip region. Therefore, a region written in a preceding main scanning and that written in the following main scanning are partially overlapped to apply full light onto the whole writing region in the apparatus of Document 1.
Japanese Patent Application Laid-Open No. 2005-243870 (Document 2) discloses a pattern writing apparatus for applying light to two scanned bands which are away from each other at one time by moving light emitted from two DMDs, instead of the apparatus where the region group irradiated with light is tilted. In the apparatus, since the order of light irradiation on all scanned bands is devised, it is possible to prevent exposures of both scanned bands on a part of borders between the scanned bands from having a long interval and prevent occurrence of a remaining film on a photoresist layer in all the borders.
It is confirmed that a degree of photo reaction by split two irradiations of an amount of light is larger than that by one irradiation of the same amount of light, depending on characteristics of a photosensitive material. In the method disclosed in Document 1, a degree of photo reaction in an overlapping area between a region irradiated with light in the preceding main scanning and that irradiated with light in the following main scanning can be inadmissibly larger than that in other area (i.e., the overlapping area is an area where writing is performed by passing the irradiation region group twice, to which the light from the micromirror group of the DMD is applied).